Inhalers are medical devices used for delivering an aerosolized medicine via the throat into the lungs of a patient suffering from respiratory disorders such as chronic obstructive pulmonary disease (COPD), emphysema, bronchitis, asthma, and the like. Inhalers typically include a pressurized canister containing the aerosolized medicine. To release the medicine a user/patient places the inhaler in his/her mouth and depresses the canister that moves intermittently to dispense a discrete amount of the medicine in aerosol form from the inhaler. The medicine is inhaled in the lungs and reaches different airways in the lungs to provide relief to the patient. Patients suffering from chronic respiratory disorders keep such inhaler with them all the time and regularly use the inhaler whenever they face difficulty in breathing which can occur when they are in crowded places, while travelling in crowded vehicles, on dusty roads, and the like. Regular use of the inhaler can lead to fast consumption of the medicine within the canister, whereby unavailability of the medicine in the inhaler at any time when a patient suffers from breathing difficulty or an asthma attack can lead to disastrous consequences for the patient.
Hence, it is imperative for a regular user/patient of the inhaler to know the amount of medicine remaining within the canister of the inhaler. To address this requirement about the amount of medicine left in the inhaler, inhalers with counting means were devised to indicate the amount of medicine remaining in the inhaler generally over a scale.
Indian Patent IN231955 mentions a mechanical counter for a metering apparatus for metering for a medicament. The mechanical counter consists of a spindle with rotary locking, whose axis extends in parallel relationship with the axis of the metering apparatus and which is disposed in the region of the peripheral surface of the apparatus. The spindle is automatically driven by way of a transmission assembly when the metering apparatus is actuated. The number of metering portions already discharged and the number of metering portions permitted in total is quasi-continuously displayed by the mechanical counter. However, such rotary counters consist of a large number of components which make the counter complex and easily susceptible to metering errors and malfunctioning.
The devices in the prior art generally employ complex counting mechanisms which are prone to metering errors due to improper handling. Hence, there is a need for metered dose inhaler having a counting mechanism that accurately counts and indicates precise quantity of medicine remaining in the inhaler.